To study the action of the pepsin enzyme under optimum conditions

 

Experiment – 2

To study the action of the pepsin enzyme under optimum conditions

Introduction

Pepsin is an enzyme that aids in the breakdown of proteins and is secreted in the stomach of most animals. It functions at a very low pH, which makes it ideal to use for studying the effect of pH on enzyme activity. Commercial or natural albumin can be used as the protein source; however hardboiled egg white is more impressive to demonstrate the action of pepsin.

 Materials

1.      Egg white (hard-boiled)

2.      Test tubes (6)

3.      Test tube rack

4.      Metric ruler

5.      Knife

 

Solutions:

1.      1.0% Pepsin

2.      0.4% Hydrochloric acid

3.      Pepsin (1.0%) in 0.4% hydrochloric acid

4.      0.5% Sodium bicarbonate

5.      Pepsin (1.0%) in 0.5% sodium bicarbonate

6.      Distilled water

 

 Procedure

1. Label test tubes A to F.
2. Fill each tube 1/3 full (5 ml) with the corresponding solution.

3. Drop a small (2 mm) cube of egg white into each tube.

4. Incubate at room temperature for approximately 12 hours. (The speed of this reaction can be increased by using very thin strips of egg white and/or incubating at 30°C. Students might want to compare the action of papain under similar conditions.)

5. Examine tubes for the presence of the egg white.

 Results

After 12 hours, the egg white will be “digested” in tube B; little, if any, of the cube will remain, while there appears to be little change in the other tubes. If allowed to incubate longer, the cube in tube D and possibly C will decrease in size.

Dr. Vidhin Kamble 

Department of Zoology

Sangola College, Sangola